Yarn tensioning device



YARN TENSIONING DEVICE Daniel I. Mindheim, Glen Cove, and Howard c. Lindemann, Westbury, N.Y., assignors to Lindly & Company, S Inc., a corporation of New York Application January 2, 1958, Serial No. 706,823 Claims. (Cl. 242-150) The present invention relates to yarn tensioning equipment, the term yarn being herein used in a generic sense to include thread, cord and other strand material.

While the invention is widely applicable to textile machinery and other equipment where the controlled tensioning of yarn is required, it is particularly suitable for installation on creels in the warping of yarn to control the tension applied to the yarn in the warping operation. i

. In warping equipment presently used, yarn coming from spools or cones on the creel is tensioned by being run between discs which are pressed together by means of springs or weights. Adjustment of tension is efiected by adding or removing weights or by tightening or loosening the springs by means of which the discs are pressed toward one another. As a tensioning device is required for each end of yarn, the individual adjustment of the tension devices presents a major task since there may be several hundred yarn ends on a single creel. Moreover, it is diflicult to obtain uniform adjustment to insure the uniformity of tension that is required in the warping operation.

In accordance with the invention, yarn tension is applied and controlled by means of electromagnetic force. With the apparatus in accordance with the present invention the force and hence the tension applied to the yarn ends of warping equipment are controlled by a simple electrical circuit making it possible to vary the tension on all of the yarn ends simultaneously from a single cntrol point. In addition to the centralized control, a preferred embodiment of the invention also provides individual regulation of the tensioning devices, for example to compensate for the fact that certain ends going from the creel to the warper pass through more guides than others and are hence subjected to greater drag. Likewise, when it is desired to subject certain yarn ends to greater tension than others, the individual tensioning devices in accordance with the invention are readily adjusted while at the same time providing central control for all of the tensioning devices.

A further advantage of the present invention is that the use of electromagnetic force instead of weights avoids the inertia inherent in the use of weights and thereby minimizes the breakage of yarn ends caused when stripbacks enter the tensioning device. In contrast with other types. of tensioning devices employing pulleys or twirlers over which the yarn ends run, the tensioning devices in accordance with the present invention are not subject to objectionable overrun. Moreover, the tensioning devices in accordance with the invention are of simple construction, are easily installed and easily cleaned and serviced.

The characteristics and advantages of the invention will be more fully understood from the following description and claims in conjunction with the accompanying drawings which illustrate by way of example a preferred embodiment. In the drawings:

atent O "ice Fig. 1 is an end view of a tensioning device in accordance with the present invention.

Fig. 2 is an axial section taken approximately on the line 22 in Fig. 1 and Fig. 3 is a diagrammatic representation of a suitable circuit controlling a plurality of tensioning devices such as are shown in Figs. 1 and 2.

In Figs. 1 and 2 there is shown by way of example a tensioning device 1 comprising a central post 2, tension discs 3 and 4 and an electromagnet 5 for drawing the discs toward one another to apply tension to a yarn Y running between them.

The electromagnet 5 has a core which is shown as comprising a circular inner core 6 having a central hole 7 and an upstanding peripheral rim 8. The core further comprises a circular cup-shaped member 10 having a bottom portion 11 underlying the core 6 and an upstanding peripheral flange portion 12 which is spaced radially from the periphery of the core 6 and projects upwardly to approximately the same height as the rim 8 ofthe core. The inner core 6 and cup 1t] are formed of iron or other magnetically permeable material, It will be seen that the inner core 6 and cup-shaped member 10 together form an annular core of channel cross; section with the inner core 6 forming the inner wall of the channel, the bottom portion 11 of the cup forming the bottom of the channel and the peripheral flange por: tion 12 forming the outer wall of the channel. An an nular winding or coil 14 is accommodated in the annular space or channel between the inner core 6 and the up.-

. standing flange or rim portion 12 of the cup 10. The

to an electric circuit as described below.

coil 14 is preferably wound on an annular plastic coil form 15 having a cylindrical inner wall 16 and outwardly, projecting flange portions 17; The winding 14 is provided with suitable terminals or leads 18 for connection The central post 2 is shown as comprising a tubular member 20 and a bolt 21 which extends down through the tubular member and through the hole 7 of the inner core 6. The bolt 21 further extends through a hole 22 in a part of the creel or other support 23 on which? the tension device is to be mounted. A nut 24 screwed, on the lower end of the bolt secures the tension device firmly in selected position. The tubular post 2% is formed of hard smooth abrasion-resistant non-magnetic material: for example a ceramic composition or chromium plated brass. The bolt 21 is likewise formed of brass or other non-magnetic material. It will be seen that the'lower end of the tubular post 20 rests on the central portion of the inner core 6 and is hence below the level of the upstanding rim portion 8.

The lower annular disc 4 rests on the upper'edges of the upstanding rims 8 and i the core and cup re' spectively It has an inner peripheral flange portion25 that projects downwardly inside the upstanding rim por-j tion 8 of the inner core 6 and loosely surrounds the central post 20. An outer rim portion 26 slopes downwardly and outwardly and is hence frusto-conical in configuration. The disc 4 is formed of non-magnetic material with at least the upper surface hard, smooth and abrasion-resistant. For example the disc may be formed of brass which is chromium plated. i

The upper annular disc 3 is similar in shape to-the lower disc but reversed. It has an inner peripheral flange portion 27 which loosely surrounds the central post 20 and constitutes a guiding sleeve for the disc. An outer peripheral rim portion 28 slopes upwardly and outwardly and is hence of frusto-conical configuration. Hence as viewed in axial section (Fig. 2) the rim portions 26 and 28 of the two discsform a V. The upper disc 3 is formedof steel or. other magnetic material and constitutes the armature of the electromagnet 5. At least the lower gnomes be easily rotatable and also slidable in an axial direction. 7

The inner peripheral flanges 25 and 27 provide large-area bearing and guiding surfaces for the discs on the central post. They also provide guiding surfaces for the yarn.

A yarn Y to which tension is to be applied is guided so as to run between the discs 3 and 4 and malte'a partial turn around the central post 2. For this purpose suitable guiding means are provided either on the tensioning device or on the creel or other associated apparatus. By way of example there is shown a guiding eye 30 which is mounted on the support 23 by a bracket 31. It will be understood that other guides are provided as desired. In the embodiment shown by way of example in Figs. 1 and 2, the yarn Y makes a quarter of a turn around the central post 2 and hence emerges at approximately right angles to its direction of entry. The conical rim portions 26 and 28 of the discs 3 and 4 facilitate threading the device. It will be seen that both of the discs 3 and 4 are freely rotatable and slidable on and easily removable from the central post for cleaning, inspection or replacement.

When the coil 14 of the electromagnet 5 is energized, for example by means of the circuit shown in Fig. 3, the resulting flux passes through a path comprising the inner core 6, cup and upper disc 3 andthereby exerts a force tending to draw the upper disc toward the electromagnet and hence toward the lower disc 4. The discs are -thereby pressed into frictional engagement with a yarn Y running between them and thus apply a frictional drag to the yarn. The amount of drag depends on the force with which the upper disc 3 is drawn toward the lower disc by the electromagnet. This force can be readily varied and controlled by regulating the current flowing through the'coil 14. As the disc 3 is of light Weight and hence relatively low inertia, the discs are readily separated by any strip-back or other enlargement occurring in the yarn so that there is no breakage of the yarn end.

In Fig. 3 there is shown by way of example an electrical circuit for controlling a plurality of associated tension devices which are designated 1a, 1b, 1c and 1d respectively and are of the construction illustrated in Figs. 1 and 2. The tension devices are shown connected in parallel between leads 35 and 36 to which current is supplied from an alternating current source 37 through a rectifier 38 and a variable resistance or potentiometer 39. It will thus be seen that the tension devices are energized by uni-directional pulsating current derived for example from a 60 cycle alternating current source. While the tension devices may, if desired, be energized by constant direct current, the use of pulsating current has beenfound to be advantageous in that the pulsating or vibrating force applied to the tension discs assists in keeping the discs clean, promotes gradual rotation of the discs so that new surfaces are continually presented to the yarn and reduces to a minimum the possibility of .the tension device snagging or stripping the yarn. A pulsating power supply also tends to prevent back-up of twist in thrown yarn or yarn with slight twist.

The potentiometer 39 is preferably located at a position convenient to the operator or attendant of the apparatus and provides means for adjusting all of the tension devices on a creel or other piece of equipment instantly and simultaneously. A switch 40 is closed to energize and opened to deenergize all of the tension devices. 7 en the tensioning devices are used with a warper, the circuit supplying current to them is preferably connected to the stop-motion of the warper so that when the latter is stopped a relay is energized to provide extra currentto the coils of the tension devices, thereby increasing the force on the yarn and preventing overrun or slackness.

invention is hence in no way limited to the tension devices, a variable resistance 41 is provided in series with each of the tension devices in addition to the central control afforded by the potentiometer 39 and switch 40. The individual resistances 41 can thus be varried to regulate the tension provided by each individual tension device for example to compensate for the fact that certain yarns may pass over more guides than others or may pass over guides at different angles so as'to .be subjected to different amounts of tension during their travel. Moreover, there may be applications where it is desired to apply greater'or lesser tension to particular yarn ends. The variable resistances 4 1 proyide individual regulation Without in any way interfering With the overall control provided by the central potentiometer 39.

While a preferred embodiment of the invention has been shown by way of example in the drawings and particularly described it will be understood that the dimensions and configuration of the tensio'ning' devices' in accordance with the invention may be varied to meet the circumstances and requirements of each application. The preferred embodiment herein shown and described.

What we claim and desire to secure by Letters Patent is:

'1. A yarn tensio'ning device for a traveling yarn; "coinprising an annular electromagnet having an annular core formed of magnetically permeable materal and having a central inner portion, a bottom portion and an annular outer wall portion spaced radially outwardly from said inner portion and forming in cross section a channel open at the top, and an annular magnet winding in saidchannel and surrounding said central portion, a central post coaxial with said electromagnet and projecting upwardly above said core, a pair of centrally apertured friction discs sur.-.

rounding said post and overlying said channel, said discs adapted'to receive said yarn between them and comprising a lowerfriction disc formed of non-magnetic material and an upper friction disc overlying said lower discia nd formed of magnetically permeablematerial, said upper disc'cos operating with said core to form a substantially closed magnetic circuit, at least said upper disc being freely rotatable and axially movable on said post, means for supplying electric current to said winding to energize said electromagnet and thereby attract said upper disc toward said core and hence toward said lowerdisc toapply tension to said traveling yarn and variable means for regulating the flow of current through said winding to increase and decrease said current and thereby adjust the amount of tension applied to said yarn.

2. in a yarn tensioning" device, an electromagnet comprising an annular coil and a core of magnetically per.- meable material having an inner core portion inside said coil, an outer core portion outside said coil and a portion connecting said inner and outer portions to define a channel receiving said coil, the side of said channel oppo, site said connecting'portion being open," a first friction member closing the open side of said channel, a second friction member overlying said first member on the side away from said core and movable toward and away from said first member, means for guiding said second member in such movement, means for guiding a yarn running between said friction members, said first friction member being of nonmagneticmaterial and said second friction member being of magnetically permeable material 'to complete a magnetic circuit comprising said inner core portion, said connecting portion, said outer core portion and said second friction member which is thereby drawn toward said core and hence .toward said first friction member when said coil is energized to grip saidyarn frictionally between said two friction members with a force dependent on the current flowing through saidcoil, and means for supplying to said coil a periodic current to apply a pulsating force to said second friction member.

In order to provide for individual regulation of the 3. A yarn tensioning device according to'c1ai'n'1.2 in

which said current supplying means supplies pulsating unidirectional current to said coil.

4. A yarn tensioning device comprising an annular electromagnet having an annular core formed of magnetically permeable material and having an inner wall portion, an annular bottom portion andan annular outer Wall portionspaced radially outwardly from said inner wall portion and forming in cross section a channel open at the top, and an annular magnet winding in said channel, a central post coaxial with said electromagnet and projecting upwardly above said core, a pair of centrally apertured friction discs surrounding said post and rotatable and axially movable thereon, said discs comprising a lower friction disc resting on the top of said channel and formed of non-magnetic material and an upper friction disc overlying said lower disc and formed of magnetically permeable material, said upper disc cooperating with said core to form a substantially closed magnetic circuit, means for guiding a travelling yarn to run between and be engaged by said discs and at least partially around said post, means for supplying electric current to said winding to energize said electromagnet and thereby attract said upper disc toward said core and hence toward said lower disc to apply tension to said travelling yarn, and variable means for regulating the flow of current through said winding to increase and decrease said current and thereby adjust the amount of tension applied to said yarn.

5. A yarn tensioning device comprising a central post,

an annular electromagnet coaxial with said post and having a bottom portion and an outer wall portion spaced radially outwardly from said rim and extending up from said bottom to approximately the same height as said rim, said inner core, bottom and outer wall portions forming an annular channel open at the top and annular magnet winding in said channel, a pair of centrally apertured friction discs surrounding said post and rotatable and axially moveable thereon, said discs comprising a lower friction disc resting on the top of said channel and having an inner peripheral flange extended down radially inside of and guided by said rim and an outer peripheral flange extending downwardly radially outside of said outer wall portion, and an upper friction disc overlying said lower disc and having upwardly extending inner and outer peripheral flanges, said lower disc being formed of non-magnetic material and said upper disc being formed of magnetically permeable material and cooperating with said core to form a substantially closed magnetic circuit, means for guiding a travelling yarn to run between and be engaged by said discs and at least partially around said post, means for supplying electric current to said winding to energize said electromagnet and thereby attract said upper disc toward said core and hence toward said lower disc to apply tension to said travelling yarn, and variable means for regulating the flow of current through said winding to increase and decrease said current and thereby adjust the amount of tension applied to said yarn.

References Cited in the file of this patent UNITED STATES PATENTS 2,614,773 Ammerall Oct. 21, 1952 2,629,561 Heizer Feb. 24, 1953 2,646,943 Lindsay July 28, 1953 2,705,362 Roughsedge Apr. 5, 1955 FOREIGN PATENTS 568,730 Great Britain Apr. 18, 1945 926,867 Germany Apr. 25, 1955 

